[21.03] Tidal Dwarf Galaxy Candidates in Arp 143's Plume

The tidal plume in the ring galaxy system Arp 143 (NGC
2444/45) is one of the largest (14.5' or 240 kpc in
projection; Ho=70 km s-1 Mpc-1) and
consequently, one of the oldest known (~750 Myr). This
makes it interesting from the standpoint of the formation
and evolution of Tidal Dwarf Galaxies (TDGs). In addition,
TDG's may represent instances of present day galaxy
formation, and are thus highly relevant for the study of
galaxy formation at early epochs.

We present high resolution VLA HI maps of Arp 143's gas
plume, which reveal an unprecedented number (25) of
condensations with sizes and HI masses characteristic of
dwarf galaxies (D>1~kpc, MHI ~108 Mo).
These data are complemented by deep WHT Prime Focus Mosaic
Camera B, R, and H-alpha images to constrain the stellar
masses and populations, and ongoing star formation activity
in the HI clumps.

We compare the stellar and HI properties of these
condensations to other TDG candidates, as well as bona fide
dwarf galaxies. We also compare the distribution and mass
function of the condensations in Arp 143's plume with models
of TDG formation. The large age difference inferred between
the HI plume (~750 Myr) and the ring in NGC 2445 (60
± 15 Myr) require multiple interactions in the Arp 143
system.